Following up on this, now that the system has some processes that are
doing something (DECnet configured to connect to HECnet again), I notice
that CPU usage is truly idling. It seems that if the system is
completely idle, then it gets that interesting ramp-up of CPU
utilization, but if a process does something every now and again (such
as sending/receiving "hello" packets), that resets things so that it
maintains very low consumption when otherwise idle.
--Marc